Methodological Principles and Applications of the Delphi Method: A Narrative Review

The appearance of complex issues with insufficient information has resulted in the consensus or unanimity spread. The consensus methods include the nominal group and the Delphi method.The Delphi method is a systematic process to predict and help making decision through survey rounds and information gathering and finally the group consensus. This method has been designed as a group communication process aiming at conducting accurate examinations and discussion of a particular issue in order to determine aims, political researches and future events prediction based on experts’ opinions. Therefore, the aim of this study is to gain a general understanding about methodology and its applications in designing different programs with due attention to the importance of this method in medical sciences research, including health. In this study, first the general structure of the Delphi study method (history, definitions, purposes and its application) is discussed.  Afterwards, different types of Delphi method, including classical, policy, decision, numerical and historical methods (along with examples for better understanding of the subject) are discussed. In the following part, the main components of  the Delphi method including recitation or repetition, experts, experts qualifications, number of experts involved in the study, controlled feedback, questionnaire, sampling method, participant anonymity, time, results analysis, and experts consensus are explained. Finally, the Delphi study process, which includes the first, second and third rounds, and studying the weaknesses and strengths, validity and reliability of the Delphi method, is studied.